Thank you for your question.
If the two screws are side by side, one is the high speed mixture screw and the other is the low speed mixture screw. To set the high and low adjustment screws, tighten the screws in until they stop, don't force the screw after it stops. Back each screw out 1 1/2 turns. The engine will start and run here if everything else is ok. Fine tune each adjustment screw by closing the screw off (CW) until the engine runs rough. Back the screw out (CCW) until the engine smooths out. Run the engine at full speed and adjust the high screw. Let off the trigger and adjust the low screw. Once the mixture screws are adjusted, you can turn the idle screw to adjust the idle speed. It can take some time getting it all adjusted.
If you can not get the carburetor adjusted, I recommend replacing the carburetor. There could be a passage plugged in the carburetor. The cost is around $27.00.
Please let me know if you need further assistance.
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